Agriculture Reference
In-Depth Information
Figure 14.28
Watermelon pretreated with 1-MCP
maintained texture during after 24 days of storage
at 13
°
C, whereas untreated fruit was unmarketable.
(Photo credit: D.J. Huber.)
Figure 14.27
Properly selected films can be used
to induce a modified atmosphere in the shipping
container.
mainly for container loads. 'Galia' melons had less decay
and better appearance after 16 days storage in 10%
oxygen/10% carbon dioxide at 6°C; use of an ethylene
absorbent further reduced decay (Aharoni
et al
. 1993).
Cartaxo (1998) reported that chunks of 'Millionaire'
seedless watermelon stored at 3°C and 5% oxygen/10%
carbon dioxide maintained low microbial counts up to 15
days, five times longer than for chunks stored in air.
Determination of optimal controlled atmosphere require-
ments for the various melons led to the development of
modified atmosphere packaging. Modified atmosphere
packaging (MAP) employs selectively permeable films to
passively establish and maintain a desired range of low
oxygen or high carbon dioxide within an enclosed
consumer package, shipping container (Figure 14.27) or
pallet (Lange 2000). It has revolutionized the produce
industry by extending the storage life of fresh-cut
vegetables, and more recently fruit that have extremely
short post-harvest life due to high sugar content. MAP
requires constant temperature since the desired atmosphere
is a factor of product respiration and transmissivity of
the film to oxygen and carbon dioxide (Garrett 1998).
A new gaseous compound, 1-methylcyclopropene
(1-MCP), is quickly becoming commercialized for treating
certain fruits and vegetables to retard ripening and senes-
cence. It is active in extremely low concentrations, <1 ppm,
and functions by inhibiting ethylene action in plant tissues
(Blankenship & Dole 2003; Huber 2008). 1-MCP slows
ripening in netted melon and protects ethylene-sensitive
crops during storage. Senescence of watermelon and
cucumber was significantly delayed during constant
exposure to 40 ppb ethylene when pretreated with 1-MCP
(Mao
et al
. 2004; Lima
et al
. 2005; Figure 14.28).
Value-added fresh produce
Increasing consumer demand for convenient and nutritious
foods since the late 1980s has driven a rapid rise in the
amount of fresh produce that is sold as fresh-cut products.
Also known as minimally processed, this fresh produce is
prepared in ready-to-eat portions. In the United States,
more than 10% of all fresh produce is currently processed
into some form of fresh-cut product, amounting to sales of
$10 to 12 billion (US dollars) (IFPA 2003). It was also
reported that 75% of respondents to a consumer survey
considered themselves regular purchasers of fresh-cut
produce, buying an item at least once per month.
Fresh-cut processing involves peeling and slicing the
fruit or vegetable into the final form. This process makes
the product extremely perishable because peeling removes
the natural barriers (waxy, epidermal tissues) to disease
micro-organisms and slicing, shredding, etc., induce
wound stress and accelerate senescent processes (Saltveit
2003). Post-harvest life of fresh-cut products is reduced to
3 days (watermelon cubes) and to 15 days (cantaloupe
cubes). For these reasons, fresh-cut produce must be of
high initial quality (e.g., commercial fresh-cut processors
must not use cull products as raw material), it must remain
cool throughout processing and sanitizing, and it must be
packed in properly designed packaging.
Edible portion varies with melon type. Ates
et al
. (1993)
reported edible portions (% of whole fruit), 62% for Piel de
Sapo 63% for Amarillo, 58% for Galia and 53% for Tendral.
